title: Ethyl (Z)-4'-(4-eth-oxy-1-hy-droxy-3,4-dioxobut-1-en-1-yl)-[1,1'-biphen-yl]-3-carboxyl-ate.
abstract: The 1,3-diketone group of the title compound, C21H20O6, exists in a keto-enol form stabilized by a strong intra-molecular O-H⋯O hydrogen bond. As a result, a planar (mean deviation = 0.0099 Å) six-membered hydrogen-bonded ring is formed. The C-O and C-C bond lengths suggest significant electron delocalization in the ring. The dihedral angle between the six-membered hydrogen-bonded ring and its adjacent benzene ring is 8.78 (5)° and that between the benzene rings is 19.70 (5)°. In the crystal, mol-ecules are packed in a layered structure parallel to the b axis through C-H⋯O and π-π inter-actions [centroid-centroid distance between stacked benzene rings = 3.868 (2) Å].
authors.affiliation: School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ugai